1. Field of the Invention
The present invention relates generally to a mobile communication system, and more particularly, to an apparatus and method for managing a Random Access CHannel (RACH) in a mobile communication system.
2. Description of the Related Art
Long Term Evolution (LTE), which is the next-generation mobile communication system of Universal Mobile Telecommunication Service (UMTS) or the third generation mobile communication system, provides high-speed packet services based on Orthogonal Frequency Division Multiplexing (OFDM).
FIG. 1 illustrates an LTE mobile communication system.
Referring to FIG. 1, the LTE system has been simplified in a 2-node structure including Evolved Node Bs (ENBs) 120, 122, 124, 126 and 128, and anchor nodes 130 and 132. A User Equipment (UE) 101 accesses an Internet Protocol (IP) network using the ENBs and the anchor nodes. The ENBs are connected to the UE 101 by radio channels, and manage their cells and control radio resources.
For example, an ENB generates control information necessary in the cell(s) as system information, broadcasts the system information, allocates radio resources to exchange data and/or control information with UEs, and decides and performs a handover by acquiring, from UEs, channel measurement information of the current cell and adjacent cells. The ENB includes control protocols such as a Radio Resource Control (RRC) associated with radio resource management.
However, a more efficient random access procedure would greatly benefit the next-generation mobile communication system. In particular, the next-generation mobile communication system is still lacking a scheme that efficiently allocates random access resources considering collisions or contentions between random access preambles, which are simultaneously transmitted from multiple UEs.